The present invention relates to an improved process for manufacturing higher alcohol sulfate or higher alcohol ethoxysulfate. More particularly the present invention relates to a process for manufacturing an aqueous solution or slurry containing a caustic alkali salt of sulfuric ester of higher alcohol or its ethoxylate in a high concentration ranging from 60 wt.% to 75 wt.%.
The aqueous higher alcohol sulfate or higher alcohol ethoxysulfate solutions or slurries are generally manufactured by sulfating higher alcohols or higher alcohol ethoxylates with sulfur trioxide or chlorosulfonic acid and then neutralizing the resulting sulfates with an aqueous caustic alkali solution. The concentrations of aqueous solutions or slurries thereby obtained are practically limited to about 30 wt.% at the highest. This is because, when it is attempted to obtain higher concentrations, the reactants or products become so highly viscous that difficulties are brought about in handling them at the time of manufacturing, transporting products and so forth. Even if this problem be solved, however, it is preferable, from the viewpoints of not only production efficiencies but also storage or transportation economies, that the aqueous sulfate solutions or slurries should be manufactured with high concentrations.
Under these circumstances, a conventional method is proposed in order to achieve the manufacture of low-viscosity and yet high-concentration sulfate solution or slurry, said method comprising allowing a viscosity-lowering substance to co-exist at the time of neutralizing the sulfuric ester. In this connection, Japanese Patent Open No. 116383/1975 discloses the method comprising the use of polyethylene glycol, Japanese Patent Open No. 80285/1977 discloses the method comprising the use of excess caustic alkali, and Japanese Patent Open No. 5089/1978 discloses the method comprising the use of sulfuric acid or sodium sulfate respectively.
However, the aqueous solutions or slurries obtained by the above mentioned conventional methods are defective in that their concentrations are about 55 wt.% at the highest, and so, when they are more highly concentrated, their viscosities are extremely increased and thus their fluidities are lost and ultimately they are gelated. In addition, the aqueous solutions or slurries obtained by the aforesaid conventional methods are disadvantageous in that since those solutions or slurries necessarily contain viscosity-lowering substances as impurities, their usages are restricted.